The protection and availability of data is an ongoing and growing concern in the computer industry. An increasingly common method of protecting data, such as configuration data or received instructions, is to provide a data cache for processors and controllers. To protect the data, the cache is provided power not only from system power sources but also a battery dedicated to the cache. This arrangement is typically referred to as “battery-backed cache” and is used to protect cached data in the event of a power outage or equipment failure, such as failure of a server, a processor, or a controller. For example, RAID (Redundant Arrays of Inexpensive Disks) controllers are typically designed to use a cache to store data in read-ahead, write-back, and other operations, and the RAID controller cache is battery-backed to retain the data during a system or power failure to allow later completion of these operations when the system restarts. In RAID and other similar systems, data availability is the overriding design concern with cost being a secondary issue, and nearly any system improvement that enhances uptime and data availability is not only useful but compelling.
While protecting data, existing battery-backed cache systems are difficult to maintain. In RAID controller systems, the battery used to provide back up power for the RAID controller cache generally has to be replaced periodically, e.g., every 1 to 3 years. In standard arrangements, the cache battery is provided on the same card or board as the RAID controller within the case or housing that structurally holds or encloses the RAID controller system. To replace the cache battery, the RAID controller system must be powered down, which requires scheduling of the maintenance as the RAID controller is unavailable during battery replacement. Then, the computer or device housing is disassembled to allow removal of the RAID/cache battery board, such as by unplugging the board from the system backplane. The battery is unscrewed or otherwise removed from the board or card, replaced with a new battery, the board or card is reinserted into the case or the backplane, and the case or housing is reassembled. The complexity of the battery replacement generally requires a technician to properly service the battery-backed cache system.
Hence, there remains a need for an improved cache battery module or system that facilitates replacement of a cache battery or other battery used to provide back up power for a computer component. Preferably, such a module or system would be adapted to reduce or eliminate the need for powering down the host or processor system. Further, it is preferable that the module or system be configured to allow customer replacement of the cache or back up battery.